Synthesis, Phase-Transition Behaviour, and Oil Adsorption Performance of Porous Poly(oligo(ethylene glycol) Alkyl Ether Acrylate) Gels

To probe the effects of pendant side-chain structures on the properties of porous thermoresponsive polymer gels, oligo(ethylene glycol) alkyl ether acrylates were polymerised in an aqueous medium under radical-mediated phase-separation conditions. The monomer structures varied according to the lengths and termini of their ethylene glycol side chains. The porous poly(oligo(ethylene glycol) alkyl ether acrylate) (POEGA) gels exhibited variable lower critical solution temperatures (LCSTs) but similar and rapid swelling–deswelling behaviours. Although the LCST of the poly(tri(ethylene glycol) monomethyl ether acrylate) (PTEGA) gel decreased with increasing aqueous NaCl or CaCl(2) concentration, PTEGA showed excellent thermosensitivity in highly concentrated salt solutions, recommending its application in saline environments. Examination of PTEGA adsorption performance in an oil–water emulsion showed that n-tridecane adsorption increased with temperature. Although n-tridecane was effectively adsorbed at 70 °C, its release from the fully adsorbed PTEGA gel was difficult despite a temperature reduction from 70 to 20 °C.